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Free download in PDF CBSE Class 12 Biology Short Questions & Answers. Here Gkseries provide Biology Solve Questions and Answers for CBSE Class 12 Students.
41
From his long term ecosystem experiments, David Tilman showed that
A
decreased diversity contributed to higher productivity
B
decreased diversity contributed to decreased productivity
C
increased diversity contributed to increased productivity
D
increased diversity contributed to decreased productivity
View Answer
Answer: increased diversity contributed to increased productivity
42
Which of the following organisation is responsible for maintaining the Red Data Book?
A
IUCN
B
USDA
C
IDRI
D
All of these
View Answer
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43
Approximately how much of the solar energy that falls on the leaves of a plant is converted to chemical energy by photosynthesis? [NCERT Exemplar]
A
2-10%
B
50%
C
Less than 1%
D
30%
View Answer
44
Which of the following ecosystems is most productive in terms of net primary production? [NCERT Exemplar]
A
Estuaries
B
Deserts
C
Tropical rain forests
D
Oceans
View Answer
Answer: Tropical rain forests
45
The reservoir for the gaseous type of biogeochemical cycle exists in [NCERT Exemplar]
A
stratosphere
B
atmosphere
C
ionosphere
D
lithosphere
View Answer
46
The sequence of communities of primary succession in water is
A
phytoplankton, rooted submerged hydrophytes, floating hydrophytes, reed swamp, sedges, meadow and trees.
B
free-floating hydrophytes, sedges, phytoplankton, rooted hydrophytes, grasses and trees.
C
phytoplankton, free-floating hydrophytes, rooted hydrophytes, sedges, grasses and trees.
D
phytoplankton, sedges, free-floating hydrophytes, rooted hydrophytes, grasses and trees.
View Answer
Answer: phytoplankton, rooted submerged hydrophytes, floating hydrophytes, reed swamp, sedges, meadow and trees.
47
Which of the following statements is correct for secondary succession?
A
It is similar to primary succession, but has a relatively fast pace..
B
It follows primary succession.
C
It begins on a bare rock.
D
It occurs on a deforested area.
View Answer
Answer: It is similar to primary succession, but has a relatively fast pace.
48
Which of the following is a pioneer species in xerarch succession?
A
Lichens
B
Sedges
C
Bryophytes
D
Phytoplanktons
View Answer
49
The last stable community in succession that is in equilibrium with the environment, is called
A
climax community
B
pioneer community
C
serai community
D
None of these
View Answer
50
In a pond ecosystem, the food chain starts with
A
Zooplanktons.
B
Small insects
C
Phytoplanktons
D
Small fishes
View Answer
51
Which of the following represents the sedimentary type of nutrient cycle?
A
Nitrogen cycle
B
Carbon cycle
C
Phosphorus cycle.
D
Oxygen cycle
View Answer
Answer: Phosphorus cycle.
52
What parameters are used for tiger census in our country’s national parks and sanctuaries? [NCERT Exemplar]
A
Pug marks and faecal pellets
B
Actual head counts
C
Pug marks only
D
Faecal pellets only
View Answer
Answer: Pug marks and faecal pellets
53
Which of the following would necessarily decrease the density of a population in a given habitat? [NCERT Exemplar]
A
Mortality and emigration
B
Natality and immigration
C
Natality > mortality
D
Immigration > emigration
View Answer
Answer: Mortality and emigration
54
A population has more young individuals compared to the older individuals. What would be the status of the population after some years? ]NCERT Exemplar]
A
It will increase
B
It will first decline and then stabilise
C
It will decline
D
It will stabilise
View Answer
55
Amensalism is an association between two species where
A
one species is harmed and other is benefitted
B
one species is harmed and other is unaffected
C
one species is benefitted and other is unaffected
D
both the species are harmed.
View Answer
Answer: one species is harmed and other is unaffected
56
Niche overlap indicates
A
mutualism between two species
B
active cooperation between two species
C
sharing of one or more resources between the two species
D
two different parasites on the same host.
View Answer
Answer: sharing of one or more resources between the two species
57
The formula of exponential population growth curve, is
A
dN/dt = rN
B
rN/dN = dt
C
dt/dN rN
D
dN/rN = dt
View Answer
58
Individuals of one kind, i.e., one species occupying a particular geographic area, at a given time form a/an
A
population
B
deme
C
community
D
biome
View Answer
59
It natality is balanced by mortality in a population at a given time, there will be a/an
A
decrease in the population size
B
increase in the population size
C
zero population growth
D
population explosion
View Answer
Answer: zero population growth
60
Mycorrhiza is an example of
A
mutualism
B
predation
C
endoparasitism
D
ectoparasitism
View Answer
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